1. Field of the Invention
The present invention relates to a process for production of polycarbonate and more particularly to a process for efficiently producing polycarbonate which is excellent in transparency and also in flame retardance, impact resistance and fluidity.
2. Description of Related Art
As polycarbonate having high flame retardance, for example, polycarbonate having a halogen-substituted phenoxy group (e.g., a pentabromophenoxy group, a tetrachlorophenoxy group, a tribromophenoxy group and the like) at the terminal thereof (Japanese Patent Publication No. 40715/1971), a copolymer of tetrahalogenobisphenolsulfone and bisphenol A (BPA) (Japanese Patent Application Laid-Open No. 123204/1976), polycarbonate having an aromatic monosulfonyl group at the terminal thereof (Japanese Patent Application Laid-Open No. 21497/1979), a copolymer of tetrabromobisphenol A and BPA (Japanese Patent Application Laid-Open No. 155233/1982), and polycarbonate having a sulfonic acid salt group at the terminal thereof (PCT Japanese Patent Application Laid-Open No. 501212/1985) are known.
These conventional polycarbonates, however, are not sufficiently satisfactory in impact resistance, fluidity or transparency although it is superior in flame retardance. That is, there has not been obtained polycarbonate which is superior in all of flame retardance, impact resisitance, fluidity, and transparency.
In addition, polycarbonate obtained using halogen-containing bisphenol and halogen-containing phenol as starting materials is known (Japanese Patent Application Laid-Open No. 136796/1976). This polycarbonate, however, is not sufficiently high in impact resistance and fluidity although it is produced using three or more different halogen-containing bisphenols as starting materials.